When a visitor accesses a website, the browser needs to check the validity status of the SSL Certificate before the content is rendered to the waiting visitor. CRLs and OCSP are standard compliant ways of doing revocation checking. The speed at which this happens depends on the reliability and performance of the CA's infrastructure, and will have a direct impact on your website performance. The shorter the validation time, the faster your website will load for website visitors.

See the Report. StartSSL's OCSP response time appears to be ten times faster than Geotrust/RapidSSL/Symantec. And I have StartSSL certficates.